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SECTION 300
SOILS AND EARTHWORK
301.00 GENERAL CONDITIONS........................................................................... 3
310.00 SCOPE........................................................................................................... 3
311.00 Inspections .......................................................................................................... 3
320.00 DEMOLITION, REMOVAL AND ABANDONMENT.............................. 4
320.01 Disposal.............................................................................................................. 4
320.02 Salvage............................................................................................................... 5
321.00 Bridges, Culverts and Other Drainage Structures........................................... 5
322.00 Pipe and Appurtenances.................................................................................. 5
323.00 Pavement and Concrete Flatwork ....................................................................... 6
330.00 SITE PREPARATION.................................................................................. 6
331.00 Clearing............................................................................................................... 6
332.00 Staking and Grade Control.................................................................................. 7
333.00 Grading Requirements ........................................................................................ 8
333.01 Grading Permit and/or Over-Excavation Permit................................................ 8
333.02 Grading Methods ............................................................................................... 8
333.03 Cut and Fill Requirements ................................................................................. 8
333.04 Topsoil ............................................................................................................... 9
340.00 EARTHWORK ........................................................................................... 10
340.01 Definitions........................................................................................................ 10
340.02 Grading Tolerances .......................................................................................... 12
340.03 Borrow ............................................................................................................. 12
341.00 Embankment Construction................................................................................ 12
341.01 Preparation of Embankment Subgrade ............................................................ 12
341.02 Embankment Material...................................................................................... 13
342.00 Excavation........................................................................................................ 16
342.01 Excavated Material .......................................................................................... 17
342.02 Excess Excavation ........................................................................................... 17
343.00 Structure Backfill ............................................................................................. 17
350.00 TRENCHING, BACKFILLING AND COMPACTING............................ 19
350.01 Special Conditions ........................................................................................... 19
350.02 Removal of Water ............................................................................................ 20
351.00 Trench Excavation for Roadways.................................................................... 20
352.00 Trench Excavation for Pipelines and Service Lines ........................................ 20
352.01 Preparation of Foundation for Pipe Laying ..................................................... 21
353.00 Bedding for Pipelines and Service Lines ...................................................... 21
354.00 Backfill for Pipelines and Service Lines.......................................................... 22
354.01 Backfill Compaction ......................................................................................... 23
355.00 Compaction Testing ......................................................................................... 24
360.00 ROADWAY EXCAVATION, BACKFILL AND COMPACTION.......... 24
361.00 Subgrade .......................................................................................................... 25
361.01 Over-Excavation for Expansive Soils.............................................................. 26
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-2
361.02 Base Course (For Composite Sections) ........................................................... 27
361.03 Lime-Treated Subgrade ................................................................................... 28
361.04 Proof-Roll Observation and Testing ................................................................ 29
370.00 RESTORATION AND CLEAN UP ........................................................... 30
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-3
SECTION 300
SOILS AND EARTHWORK
301.00 GENERAL CONDITIONS
Refer to Section 100 Title, Scope, and General Conditions of these CONSTRUCTION
STANDARDS & SPECIFICATIONS for additional requirements that apply to all projects
within Elbert County.
310.00 SCOPE
All site work and earthwork shall comply with the requirements of these CONSTRUCTION
STANDARDS & SPECIFICATIONS and any special criteria established by Elbert County. Site
work shall be completed as shown on the approved engineering plans. Site work shall consist of
demolition, removal, and abandonment; clearing and grubbing; overlot grading; removal of
topsoil; site preparation; embankment subgrade preparation; embankment fill; excavation,
trenching, bedding and backfill of pipelines and service lines; excess excavation; structure
backfill; roadway excavation, backfill and compaction; borrow; and restoration and cleanup. All
workmanship and materials shall be in accordance with the requirements of these
CONSTRUCTION STANDARDS & SPECIFICATIONS and shall conform to the lines, grades,
quantities, and the typical cross-sections shown on the approved plans, or as directed by the
Road & Bridge Superintendent / Elbert County Engineer.
311.00 Inspections
Refer to Section 154.00 Inspections of these CONSTRUCTION STANDARDS &
SPECIFICATIONS.
Adequate inspections assure compliance to Elbert County requirements and are the basis for
Elbert County’s recommendation that said improvements be accepted for maintenance and for
release of performance guarantees. It is the responsibility of the Contractor to contact the
Road & Bridge Superintendent / Elbert County Engineer a minimum of one (1) full working
day (twenty-four [24] hours) in advance of the required inspections. Required inspections
shall include:
A. Erosion Control – Ensure that the Erosion Control Plan is adhered to and
Best Management Practices (BMP’s) are properly installed and
maintained.
B. Testing – Verify that a Colorado Registered Professional Engineer (or
designated representative), who practices the field of Geotechnical
Engineering, is onsite and that adequate testing is performed. FULL-
TIME OBSERVATION AND TESTING IS REQUIRED FOR
OVER-EXCAVATION WORK.
C. Certification – Verify that the extent and depths of proposed work is
certified. Verify the final grade.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-4
The Contractor shall provide access to all Elbert County Inspectors/Representatives, and
all other project quality control (QC) and/or quality assurance (QA) personnel throughout
the earthwork process for observation and testing purposes. The Contractor shall not
proceed with work until the project Soils Engineer has performed adequate observations
and testing, unless approved by the Road & Bridge Superintendent / Elbert County
Engineer.
All testing and retesting to meet requirements and specifications shall be at the
Contractor’s expense.
320.00 DEMOLITION, REMOVAL AND ABANDONMENT
The Contractor shall remove—wholly or in part—and satisfactorily dispose of all foundations,
signs, structures, fences, old pavements, abandoned pipelines, traffic control device materials and
any other obstructions which are not designated on the approved plans or allowed to remain.
Utilities and other items for which other provisions have been made for removal shall follow
demolition; removal and abandonment procedures shown on the approved plans or as otherwise
approved by Elbert County Removal of sign panels shall include all work necessary to remove
the panel and its attachment hardware from the existing installation. Concrete sign post bases
shall be removed. Pedestals and bases shall be removed to one (1) foot below the surrounding
ground or subgrade, and backfilled with suitable material.
Where portions of structures shall be removed, the remaining parts shall be prepared to
accommodate the new construction. The work shall be performed in such a manner that
materials left in place shall be protected from damage. All damage to portions of structures to
remain shall be repaired at the Contractor’s expense. Reinforcing steel that projects from a
structure to remain shall be cleaned and aligned to provide an adequate bond with new
construction. Dowels shall be securely grouted with an approved grout. Depressions which
result from removal of structures, footings, and other obstructions, shall be filled and compacted
with clean fill materials or an approved CLSM (“Flowable fill”) mixture so as to eliminate
hazards such as cave-in or accumulation and ponding of water.
Materials used for traffic detour structures supplied by the Contractor shall be the property of the
Contractor. After the detour is abandoned, the Contractor shall completely remove the traffic
detour structure materials and disposal of materials shall comply with Section 320.01 Disposal of
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
After all demolition, removal and abandonment work is complete, the Contractor shall grade the
entire contract area by properly filling, compacting, and leveling the site to existing adjacent
grades or to lines and grades shown on the approved plans.
320.01 Disposal
The Contractor shall make all necessary arrangements for obtaining suitable disposal
locations. If disposal shall be at other than established dumpsites, the Road & Bridge
Superintendent / Elbert County Engineer may require the Contractor to furnish written
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-5
permission from the property owner on whose property the materials and debris is
proposed to be placed. Materials and debris shall be disposed of in a manner approved
by the Road & Bridge Superintendent / Elbert County Engineer and Elbert County
Environmental Health. Burning shall not be allowed without prior written approval of
the Road & Bridge Superintendent / Elbert County Engineer, the Elbert County
Environmental Department and the governing fire district.
320.02 Salvage
All salvageable material shown on the approved plans and any additional salvageable
material marked by Elbert County shall be removed without unnecessary damage in
sections or pieces which may be readily transported and shall be stored by the Contractor
in locations approved by the Road & Bridge Superintendent / Elbert County Engineer.
The Contractor shall be required to replace any materials lost from improper storage
methods or damaged by negligence. These materials include, but shall not be limited to,
manhole frames and covers; inlet grates; valves and fire hydrants; landscape plant
materials; fence materials; handrails; culverts; guardrail; walkway; roadway and traffic
appurtenances (traffic signals and attached hardware, including mast arms and span wire)
and irrigation systems and appurtenances.
321.00 Bridges, Culverts and Other Drainage Structures
Bridges, culverts, and other drainage structures in use by traffic shall not be removed until a
Traffic Control Plan has been approved by the County Engineer or Road & Bridge
Superintendent / Elbert County Engineer. Refer to Section 141.12 Traffic Control, Barricades
and Warning Signs of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
Unless otherwise directed, the foundations or substructures of existing structures shall be
removed down to one (1) foot below natural ground surface or bottom of drainageway.
Where such portions of existing structures lie wholly or in part within the limits of a new
structure, they shall be removed as necessary to accommodate construction of the proposed
structure. Steel, concrete, and wood bridges shall be dismantled. Steel members to be
salvaged shall be match-marked by Elbert County or the Contractor with waterproof paint.
322.00 Pipe and Appurtenances
All pipe and appurtenances to be taken out of service shall be completely removed or
abandoned in place, as required by the Road & Bridge Superintendent / Elbert County
Engineer.
Pipe designated to be reused shall be removed and stored, when necessary, to prevent loss or
damage before relaying.
Excavation required to remove pipe or appurtenances shall be backfilled and compacted in
accordance with Section 350.00 TRENCHING, BACKFILLING AND COMPACTING of
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-6
When pipe is to be abandoned in place, it shall be completely filled with fly ash slurry
composed of approximately sixty-five (65) percent Class C fly ash and thirty-five (35) percent
water, unless otherwise approved by the Road & Bridge Superintendent / Elbert County
Engineer. Each end of the pipe shall be capped with concrete.
When removing appurtenances such as manholes, catch basins, inlets etc., any live lines
connected to these appurtenances shall be properly bypassed and shall remain in operation
until abandonment is complete.
When appurtenances are to be abandoned in place, the remaining structure shall be lowered to
a minimum of three (3) feet below finished grade, and shall be filled with concrete with a
minimum compressive strength of 3000 psi (at 28 days) to the top of the remaining structure
and then backfilled and compacted to the required grades.
323.00 Pavement and Concrete Flatwork
All concrete or asphalt to remain shall have a straight, true break line and a vertical face.
Concrete or asphalt may be cut with a cutting wheel, jackhammer, or saw. The Road &
Bridge Superintendent / Elbert County Engineer may require that saw-cutting be performed.
Any damage to adjacent concrete or asphalt to remain in place shall be repaired at the
Contractor’s expense. The minimum depth of saw cuts in concrete shall be two (2) inches.
If areas cut for future placement of concrete or asphalt adjacent to existing asphalt or concrete
are left exposed for longer than thirty (30) days or are subjected to inclement weather, the
areas shall be evaluated by a Geotechnical Engineer and a recommendation shall be provided
to Elbert County. An additional cut of at least six (6) inches behind and/or below the existing
structure—or until competent subgrade is encountered—may be required by the Road &
Bridge Superintendent / Elbert County Engineer.
The Contractor shall be responsible for the cost of removal and replacement of all overbreak
as determined by the Road & Bridge Superintendent / Elbert County Engineer.
330.00 SITE PREPARATION
The Contractor shall complete all work necessary to properly prepare the site as shown on the
approved plans and as specified herein. The site shall be prepared in such a manner that
facilitates subsequent soils or earthwork operations. Site preparation includes clearing, grubbing,
grading, tree and shrub removal, native grass stripping and removing and disposing of all debris
within the limits of the project and other such areas as may be indicated on the plans or required
by the work. Site preparation procedures shall be performed to comply with the approved plans
or as designated by Elbert County. Adjacent vegetation and other items to remain shall be
adequately preserved from injury.
331.00 Clearing
All sites to receive fill shall be cleared of organic materials, including root structures, at the
Contractor’s expense. Vegetation shall be pulled or grubbed in such a manner as to assure
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-7
complete and permanent removal. Branches of trees extending over the roadbed shall be
trimmed to give a clear height of twenty (20) feet above the road bed surface. All surface
objects and trees, stumps, roots and other protruding obstructions not designated to remain
shall be cleared and/or grubbed as required. Non-biodegradable, solid objects located at least
two (2) feet below the final subgrade surface may remain at the discretion of the Road &
Bridge Superintendent / Elbert County Engineer.
Elbert County may establish clearing lines and designate items and materials to remain. The
Contractor shall preserve all materials and items to remain. Paint used for cut or scarred
surfaces of trees or shrubs to remain shall be an approved asphalt base paint formulated
especially for tree surgery.
Except in areas to be excavated, stump holes and other holes from which obstructions are
removed shall be backfilled with suitable material and compacted in accordance with these
CONSTRUCTION STANDARDS & SPECIFICATIONS.
The Contractor shall scalp areas where excavation or embankment shall be made. Scalping
shall include the removal of organic material such as brush, roots, sod, grass, residue of
agricultural crops, sawdust, and vegetable matter from the surface of the ground.
Fill shall be placed on competent subgrade as determined by the project Soils Engineer. The
Contractor shall excavate soft, yielding, over-saturated, or otherwise unsuitable soils prior to
the placement of fill.
Clearing shall be performed with due consideration and protection of the general public and
public and private property. Any damage to streets, parking lots, utilities, plants, trees,
buildings or structures on public or private property, or to bench marks and construction
staking due to the negligence of the Contractor, shall be repaired and restored to its original
condition at the Contractor’s expense. Areas proposed to be preserved shall be clearly staked
or fenced off by the Contractor. It shall be the Contractor's responsibility to ensure that these
areas are not damaged during the construction process. Any damaged areas shall be repaired
or replaced at the Contractor's expense.
332.00 Staking and Grade Control
Control and construction stakes shall be set by field parties under the supervision of a
Colorado Registered Professional Engineer or a Colorado Registered Land Surveyor who
shall be paid by the Contractor. These field parties shall be available to check field control
and to provide assistance to the Contractor. A set of approved plans shall be kept on the job
site at all times by the Contractor.
It shall be the responsibility of the Contractor to maintain the alignment and grade shown on
the approved plans. The alignment and grade elevation of forms shall be checked, and any
necessary corrections shall be made before placing the concrete. When any form has been
disturbed or any subgrade thereunder has become unstable, the subgrade shall be
reconditioned or replaced in accordance with these CONSTRUCTION STANDARDS &
SPECIFICATIONS.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-8
333.00 Grading Requirements
333.01 Grading Permit and/or Over-Excavation Permit
A Grading Permit and/or Over-Excavation Permit shall be required when a property’s
improvement includes 300 or more cubic yards of cut or fill and as specified in Section
151.00 Public/Private Improvement Permit (PPIP), Grading Permit, and Over-Excavation
Permit of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
333.02 Grading Methods
All areas disturbed during grading operations shall have the final graded area hydro
seeded or revegetated with native grasses in accordance with the requirements of Section
1000 LANDSCAPE STANDARDS FOR DEVELOPMENT PROJECTS of these
CONSTRUCTION STANDARDS & SPECIFICATIONS. SEEDING SHALL BE
COMPLETED WITHIN SIXTY (60) DAYS OF THE GRADING COMPLETION
AND NO LONGER THAN ONE HUNDRED EIGHTY (180) DAYS OF THE
COMMENCEMENT OF GRADING OPERATIONS AT THE SITE.
The Contractor shall comply with all dustproofing requirements of Section 141.11
Dustproofing of these CONSTRUCTION STANDARDS & SPECIFICATIONS for the
duration of the project.
Grading shall be performed by an approved means. Areas adjacent to structures and
other areas inaccessible to heavy grading equipment shall be graded by approved manual
methods. Grading of filled and unfilled areas shall be to the lines and grades indicated on
the approved plans. Grading shall be performed in conjunction with all necessary
clearing, grubbing, stripping, filling, and compacting operations.
Final grading shall be performed to provide proper drainage for the overall site and away
from site improvements that may be sensitive to moisture infiltration. In no case shall
drainage from the project site be altered or controlled in a manner that may result in
damage, or the potential for damage, to adjacent property or to any portion of the work
from erosion or flooding.
333.03 Cut and Fill Requirements
All areas with slopes greater than fifteen (15) percent shall be benched or modified by an
approved method prior to receiving fill. Benching dimensions shall be determined by the
project Soils Engineer.
All fill shall be placed in a controlled state—tested for moisture and density—in locations
designated in the approved plans and reports and in accordance with these
CONSTRUCTION STANDARDS & SPECIFICATIONS, unless otherwise approved by
the Road & Bridge Superintendent / Elbert County Engineer. FILL MATERIALS
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-9
SHALL NOT BE PLACED, STOCKPILED OR STORED IN AN AREA THAT IS
NOT DESIGNATED ON THE PLANS OR APPROVED BY THE ROAD &
BRIDGE SUPERINTENDENT / ELBERT COUNTY ENGINEER.
The Contractor shall comply with all federal and state environmental laws, such as the
Endangered Species Act, Federal Emergency Management Act, Army Corps of
Engineers Wetlands Regulations, and Division of Wildlife Regulations. Contractor shall
make every effort to relocate wildlife prior to grading. Relocation plans shall be
approved by Elbert County. All wetlands shall be protected by silt fencing and other
required Best Management Practices (BMP’s) during grading operations and until
disturbed areas are fully revegetated.
Upon completion of work in which a Grading Permit or Over-Excavation Permit is
required, the Contractor shall provide the following information, certified and sealed by a
Colorado Registered Professional Engineer:
A. An “as-built” area grading plan which shows original ground surface
elevations, as-constructed ground surface elevations, limits and depths of
over-excavation, lot drainage patterns and locations and elevations of all
surface and subsurface drainage facilities.
B. An overlot grading summary report prepared by the project Soils Engineer
which states that fill placement is in conformance to approved plans and
reports and includes locations and elevations of field density tests
(referenced from a permanent landmark or permanent control point),
summaries of field and laboratory tests and any other substantiating data
and comments regarding deviations from the approved plans and reports
and how they relate to or affect recommendations in the approved
Geotechnical Engineering Report and grading plan.
C. A geological report prepared by an engineering geologist that includes a
final description of the geology of the site, including any new information
disclosed during the grading and how it relates to or affects
recommendations in the approved Geotechnical Engineering Report and
grading plan.
333.04 Topsoil
The Contractor shall salvage within the project limits, or acquire when needed, loose
friable loam (“topsoil”) reasonably free of admixtures of subsoil, refuse, stumps, roots,
rocks, brush, weeds, heavy clay, toxic substances or other material which would be
detrimental to the proper development of vegetative growth.
Topsoil shall not be placed until the areas to be covered have been properly prepared and
grading operations in the area have been completed. Topsoil shall be placed, spread and
keyed to the underlying material at locations and to the thickness shown on the approved
plans.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-10
Topsoil shall not be incorporated into any embankment fill or backfill material without
prior approval of the project Soils Engineer and the Road & Bridge Superintendent /
Elbert County Engineer.
340.00 EARTHWORK
Earthwork shall consist of excavation, disposal, shaping and compaction of all material
encountered within the limits of the project, including but not limited to excavation of ditches
and channels, surface boulders, muck, rock, concrete foundations, slabs, stripping, etc.
Excavation shall be performed to the line and grade and typical cross-sections shown on the
approved plans or as required by the Road & Bridge Superintendent / Elbert County Engineer.
Excavation, dewatering, sheeting, and bracing shall be performed so as to eliminate any
possibility of undermining or disturbing the foundation of any existing structures, utilities,
pavement and concrete flatwork.
Free-running water shall be drained from all earthwork materials prior to construction of
structures, utilities, or concrete flatwork construction.
The Road & Bridge Superintendent / Elbert County Engineer may require the Contractor to
submit a proposed earth-moving diagram and map of proposed haul routes for approval.
340.01 Definitions
A. Suitable Material - Any earthen material that consists of onsite or similar
non-organic sands, gravels, clays, silts and mixtures thereof with a
maximum size of six (6) inches. Claystone fragments exceeding three (3)
inches in particle size are not to be incorporated in embankment material
unless specifically approved by the project Soils Engineer and the Road &
Bridge Superintendent / Elbert County Engineer.
B. Bedrock that breaks down to specified soil types and sizes during
excavation, hauling and placement may be considered as suitable material.
C. Unsuitable Material - Any earthen material that contains vegetable or
organic silt, topsoil, frozen materials, trees, stumps, certain man made
deposits, or industrial waste, sludge or landfill, lignite, or other
undesirable materials.
D. Unclassified Excavation - Any and all earthen materials encountered,
including rocks and boulders, during construction. Rock formations that
can be removed by ripping with a D-9 tractor in good repair with a single
hydraulic ripper are considered as unclassified excavation.
E. Embankment Construction - Earthwork including preparation of the
subgrade upon which embankment material shall be placed; dikes within
or outside right-of-way; placement and compaction of approved material
within areas where unsuitable materials have been removed; and
placement and compaction of embankment materials in holes, pits and
other depressions to lines and grades shown on the approved plans. Only
suitable materials approved by the project Soils Engineer shall be used in
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-11
construction of embankments and backfills. Claystone fragments
exceeding three (3) inches in particle size are not to be incorporated in
embankment material unless specifically approved by the project Soils
Engineer and the Road & Bridge Superintendent / Elbert County Engineer.
F. Structure Excavation - Excavation of any and all materials over an area
extending three (3) feet out from the outer most bottom edge of a proposed
structure, up to existing grade or top of proposed grade (whichever comes
first) at a one to one (1:1) slope. Rock formations within this area that can
be removed by ripping with a D-9 tractor in good repair with a single
hydraulic ripper shall be considered structure excavation.
G. Structure Backfill - Earthen material that is installed around and over any
structure shown on the approved plans. Imported structure backfill (Class
I) shall meet the general gradation of “Class 1 Structure Backfill Material”
as specified in Section 703.08 of the CDOT Standard Specifications for
Road and Bridge Construction. Onsite Class 2 structure backfill shall also
meet the requirements of Section 703.08 of the CDOT Standard
Specifications for Road and Bridge Construction. Materials which do not
comply with these requirements may be used at the discretion of the
project Soils Engineer and the Road & Bridge Superintendent / Elbert
County Engineer.
H. Rock Excavation - Igneous, metamorphic or sedimentary rock formations
that cannot be excavated with a D-9 tractor in good repair with a single
hydraulic ripper.
I. Borrow - Backfill or embankment material which shall be acquired from
designated borrow areas to make up the deficient areas which cannot be
completed from excavation within work limits. All sources of borrow
material shall be approved prior to use by the project Soils Engineer and
the Road & Bridge Superintendent / Elbert County Engineer.
J. Proof-Rolling - The application of test loads over a subgrade surface by
means of a heavy pneumatic-tired vehicle to locate weak areas in
subgrade. Refer to Section 361.04 Proof-Roll Observation and Testing of
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
K. Bedding Material - Material that is installed under and around pipelines,
rip-rap, low flow channels, and any other locations required by the Road
& Bridge Superintendent / Elbert County Engineer. The thickness and
gradation of bedding materials shall comply with Section 352.00 Bedding
for Pipelines and Service Lines of these CONSTRUCTION
STANDARDS & SPECIFICATIONS.
L. Stabilization Material - Material which shall be placed in over-excavation
areas, areas with unsuitable in situ material, or areas with a high water
table in order to stabilize the existing material. Thickness of stabilization
material shall be determined and installed in the field, on a case by case
basis. Gradation of stabilization material shall comply—at a minimum—
with the “No. 4 Coarse Aggregate” specified in Section 703.02 of the
CDOT Standard Specifications for Road and Bridge Construction, or
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-12
other materials such as lime or flyash specified on the approved plans and
approved by the project Soils Engineer.
340.02 Grading Tolerances
All earthwork shall performed in such a manner that final grades after excavation,
compaction of backfill, placement of rip-rap, construction of channel lining, etc. shall
conform to the cross-sections shown on the approved plans. The final earthwork shall
comply with the design elevations, with the following allowable tolerances:
A. 0.03 feet within main drainage channel bottom limits
B. 0.3 feet at the top of any embankment where a cut side slope intersects the
existing grade
C. 0.5 feet in all portions of the site not included in items a. or b. above.
D. In addition to the above tolerances, positive surface drainage shall be
provided on the entire site so that no depressions or ponds are formed,
regardless of depth.
It shall be the Contractor's responsibility to ensure that all portions of the site drain as
shown on the approved plans.
340.03 Borrow
It shall be the Contractor's responsibility to stockpile suitable materials for use in the
project. Only after the Contractor estimates that sufficient suitable backfill material is
stockpiled to complete all earthwork operations of the project, shall excavated material be
removed from the project site.
If the Contractor fails to preserve onsite, sufficient suitable material, and removes or
disposes of suitable material, suitable material shall be recovered at the Contractor’s
expense.
If there is an insufficient quantity of suitable material available onsite, the Contractor
shall provide additional suitable material, as defined in Section 340.01 Definitions of
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
341.00 Embankment Construction
Embankment construction shall include placement, processing and compaction of all
embankment material, and all related work required to ensure proper bond of materials with
previously placed embankment material.
341.01 Preparation of Embankment Subgrade
No excavation shall be performed in any area until the proposed work has been staked by
the Contractor, cross-sections of existing ground are determined and plotted, and all
survey elevations and cross-sections shown on the approved plans are reviewed and
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-13
approved by the Road & Bridge Superintendent / Elbert County Engineer. Excavation
shall be performed to the lines and grades shown on the approved plans.
The grade shall be maintained so that the surface is well drained at all times. When
necessary, temporary drain systems shall be installed to intercept or divert surface water
that may affect the work.
Where an embankment shall be constructed, unsuitable material shall be removed from
the surface. The cleared surface shall be plowed or scarified to a minimum depth of six
(6) inches. The embankment area shall adhere to the density and moisture content
requirements shown in the following table, unless otherwise approved by the project
Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer:
Soil Classification
AASHTO M145
Relative Compaction
By Standard Proctor
ASTM D698 or
AASHTO T99
(percent
compaction)
Relative Compaction
By Modified Proctor
ASTM D1557 or
AASHTO T180
(percent
compaction)
Moisture Content
Range
(with respect to
Optimum Moisture
Content)
A-1, A-2, A-3 - 95 -2 to +2
(based on AASHTO T180)
A-4, A-6, A-7 95 - -1 to +3
(based on AASHTO T99)
Where embankments shall be placed on slopes steeper than 4:1 (horizontal to vertical),
benches shall be excavated into the slope by a method approved by the project Soils
Engineer and the Road & Bridge Superintendent / Elbert County Engineer. Such slopes
include natural and previously constructed embankments. The benches shall be cut ten
(10) feet horizontally into the existing slope to create a stepped bench condition, and the
vertical step shall not exceed four (4) feet, unless otherwise approved by the project Soils
Engineer and the Road & Bridge Superintendent / Elbert County Engineer. All surfaces
to receive embankment material shall be inspected and approved by the project Soils
Engineer immediately prior to embankment material placement.
341.02 Embankment Material
No embankment material shall be placed until approved in writing by the Owner.
Earthmoving equipment, watering equipment, processing equipment and compaction
equipment are the responsibility of the Contractor. Equipment shall be suitable for
performing excavation and embankment work in accordance with these
CONSTRUCTION STANDARDS & SPECIFICATIONS and the Contract schedule. If
at any time the moisture-conditioning or processing equipment cannot apply moisture or
process at a rate equal to or greater than the rate required to achieve an embankment
material within the required size tolerances, uniformity, and moisture contents,
embankment material placement shall be suspended at that area until it is demonstrated to
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-14
the project Soils Engineer and the Road & Bridge Superintendent / Elbert County
Engineer that all questionable areas comply with these CONSTRUCTION
STANDARDS & SPECIFICATIONS.
Equipment shall be operated in accordance with manufacturer's recommendations and
instructions and shall be maintained so that it delivers the rated energies and compactive
efforts.
IF EQUIPMENT IS DEEMED INADEQUATE, THE PROJECT SOILS
ENGINEER AND/OR THE ROAD & BRIDGE SUPERINTENDENT / ELBERT
COUNTY ENGINEER MAY RECOMMEND THE USE OF LARGER OR
DIFFERENT TYPES OF EQUIPMENT.
After subgrade is properly prepared, the embankment filling operation shall begin in the
deepest part of the area to be filled. Embankment material shall be placed and compacted
in parallel layers until the finished rough grade is reached. Temporary gaps through the
embankment shall not be allowed without approval of the Road & Bridge Superintendent
/ Elbert County Engineer. All temporary slopes shall not be steeper than 4:l
(horizontal:vertical).
THE THICKNESS OF EACH LAYER SHALL NOT EXCEED SIX (6) INCHES
BEFORE COMPACTING.
Embankment material shall be a homogenous mixture of suitable material. No particle
size shall exceed six (6) inches, and no claystone fragment shall exceed (3) three inches.
The characteristics of the material shall be in accordance with that of ‘suitable material’
as defined in Section 340.01 Definitions of these CONSTRUCTION STANDARDS &
SPECIFICATIONS. The full depth of each layer shall be processed to ensure a
satisfactory bonding surface for the next layer of embankment material.
In order to achieve uniform moisture content throughout the materials in the layer,
wetting or drying of the material and manipulation shall be performed. Placement of
material shall not proceed until excessively wet material has been dried and overly dry
material has been wetted with methods approved by the project Soils Engineer. Each
layer of embankment shall be properly processed by disking or by other approved
methods so that the water is distributed uniformly throughout the layer prior to rolling
and after compaction. In no case shall additional embankment material be placed until
the underlying layer has been properly processed in accordance with these
CONSTRUCTION STANDARDS & SPECIFICATIONS. Materials placed that do not
comply with moisture and/or density specifications are subject to removal and
replacement and/or reprocessing at the Contractor’s expense.
The surfaces of previously placed embankment material and foundation areas that have
not had material placed on them for a period of time sufficient to allow those surfaces to
comply with the specified moisture content and/or density requirements, the surface
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-15
material shall be re-processed until it complies with the requirements, prior to placement
of additional material.
If hauling equipment is used to obtain compaction, the Contractor shall route its
equipment at all times, both when loaded and when empty, over the layers as they are
placed and shall distribute the travel evenly over the entire width of the embankment.
The equipment shall be operated in such a manner that hardpan, cemented soils, clay, or
other chunky soil material shall be broken up into smaller particles and become
incorporated with the other material in the layer.
Rock Material In Common Embankment: Excavated material that contains solid rock
consisting of cobbles, boulders or rock fragments (“rock material”) less than one cubic
yard in volume; a maximum thickness of one and one-half (1½) feet; and a maximum
dimension of six (6) feet that cannot be processed by crushing, breaking or pulverizing,
may be placed in embankments below ten (10) feet from the rough subgrade elevation
with approval from the project Soils Engineer and the Road & Bridge Superintendent /
Elbert County Engineer. In no case shall claystone fragments larger than five (5) inches
in any dimension be incorporated into the embankment layers. Rock material does not
include the claystone bedrock formations common throughout Elbert County. If placed,
rock material shall be incorporated in layers no thicker than the thickness of the largest
pieces. The rock material shall be carefully dispersed throughout the layers and
throughout the embankment to avoid nesting. Rock fragments shall be spaced far enough
apart to allow the Contractor's equipment to operate between the rock pieces. All voids
shall be filled with fines material to obtain the required uniform density around the rock
fragments.
Embankment areas that contain rock material shall be compacted with adequate
equipment and sufficient passes to ensure that the embankments meet all specified
moisture and density requirements for common embankment before the next lift is
placed. The Contractor shall perform a test fill to demonstrate satisfactory compliance
with these specifications prior to placing rock material.
The Contractor shall maintain the embankment during the warranty period.
341.02.01 Embankments Twelve (12) Feet or Less in Depth
Compaction operations shall continue until each layer of embankment material for
embankments less than twelve (12) feet in height is compacted to moisture and
density requirements shown in the following table, unless otherwise required by
the project Soils Engineer and the Road & Bridge Superintendent / Elbert County
Engineer:
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-16
Soil Classification
AASHTO M145
Relative Compaction
By Standard Proctor
ASTM D698 or
AASHTO T99
(percent compaction)
Relative Compaction
By Modified Proctor
ASTM D1557 or
AASHTO T180
(percent compaction)
Moisture Content
Range
(with respect to Optimum
Moisture Content)
A-1, A-2, A-3 - 95 2 to +2
(based on AASHTO T180)
A-4, A-6, A-7 95 - -1 to +3
(based on AASHTO T99)
341.02.02 Embankments Greater Than Twelve (12) Feet in Height
Compaction operations shall continue until each layer of embankment material for
embankments greater than twelve (12) feet in height is compacted to the moisture and
density requirements shown in the following table, unless otherwise required by the
project Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer.
Soil Classification
AASHTO M145
Relative Compaction
By Standard Proctor
ASTM D698 or
AASHTO T99
(percent compaction)
Relative Compaction
By Modified Proctor
ASTM D1557 or
AASHTO T180
(percent compaction)
Moisture Content
Range
(with respect to Optimum
Moisture Content)
A-1, A-2, A-3 - 96 -2 to +2
(based on AASHTO T180)
A-4, A-6, A-7 100 - -1 to +2
(based on AASHTO T99)
342.00 Excavation
All excavated areas shall be graded in a manner that allows adequate drainage and does not
disturb material outside the limits of slopes. Excavated areas shall be within the tolerances
noted in Section 340.02 Grading Tolerances of these CONSTRUCTION STANDARDS &
SPECIFICATIONS. When practical, all suitable material removed from the excavation shall
be used in the formation of embankments, for backfilling, and for other purposes. Materials
that are considered unsuitable material (including rock) or surplus by the Road & Bridge
Superintendent / Elbert County Engineer shall be disposed of at the Contractor’s expense, in
accordance with Section 320.01 Disposal of these CONSTRUCTION STANDARDS &
SPECIFICATIONS.
All water pumped or drained from the work shall be disposed of according to provisions of
the Stormwater Discharge Permit (NPDES) in a manner satisfactory to the Road & Bridge
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-17
Superintendent / Elbert County Engineer/ Elbert County Health, without undue interference
with other work or damage to pavements, other surfaces, or property.
342.01 Excavated Material
Excavated material shall be placed so as to minimize the inconvenience to occupants
traveling on streets and driveways or adjoining properties. Excavated material shall not
be deposited on private property unless written consent of the property owner(s) has been
filed with the Road & Bridge Superintendent / Elbert County Engineer.
Suitable excavated material shall be used as backfill, fill for embankments, or other parts
of the work in accordance with the appropriate sections of these CONSTRUCTION
STANDARDS & SPECIFICATIONS.
Disposal of surplus material shall be in accordance with Section 320.01 Disposal of these
CONSTRUCTION STANDARDS & SPECIFICATIONS.
342.02 Excess Excavation
If in the opinion of the project Soils Engineer or the Road & Bridge Superintendent /
Elbert County Engineer, the material at or below the depth to which excavation for
structures would normally be carried is unsuitable for the required installation, it shall be
removed to such widths and depths as directed by the project Soils Engineer or the Road
& Bridge Superintendent / Elbert County Engineer and shall be replaced to provide a
stable, non-yielding surface that is approved by the project Soils Engineer and the Road
& Bridge Superintendent / Elbert County Engineer.
It is the sole responsibility of the Contractor to become familiar with the existing
conditions and potential excess excavation at each project site. Geotechnical reports or
other data provided by Elbert County may be used to assist in determining general site
and soil characteristics.
If, through failure or neglect of the Contractor to conduct the excavation work in a proper
manner, the surface of the subgrade is in an unsuitable condition for proceeding with
construction, the unstable material shall be removed and replaced with recycled concrete,
structure backfill, or other approved material at the Contractor’s expense. The condition
of the subgrade shall be approved by the project Soils Engineer and the Road & Bridge
Superintendent / Elbert County Engineer before any additional materials are placed.
343.00 Structure Backfill
Structure backfill shall comply with Section 340.01 Definitions of these CONSTRUCTION
STANDARDS & SPECIFICATIONS. Structure backfill material shall have a liquid limit not
exceeding thirty-five (35) and a plasticity index less than fifteen (15), as determined by
AASHTO T 89 and T 90, unless otherwise approved by the project Soils Engineer and the
Road & Bridge Superintendent / Elbert County Engineer.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-18
Areas adjacent to structures and other areas inaccessible to mobile compaction equipment
shall be compacted with suitable power-driven hand tampers or other approved devices.
Backfilling shall consist of placing materials in horizontal, uniform layers brought up
uniformly on all sides of the structure. THE THICKNESS OF EACH LAYER OF
BACKFILL SHALL NOT EXCEED SIX (6) INCHES BEFORE COMPACTING TO
THE REQUIRED DENSITY.
Backfill material shall not be deposited against the back of concrete abutments, concrete
retaining walls, or the outside of cast-in-place concrete structures until the concrete has
developed a strength of not less than eighty (80) percent of the required design strength.
Backfill placed within two (2) feet of any structure shall be placed evenly on all sides to avoid
unequal lateral pressures.
Compaction equipment or methods that produce horizontal or vertical earth pressures which
may cause excessive displacement or may damage structures, shall not be used.
Unless otherwise shown on the approved plans or directed by the Road & Bridge
Superintendent / Elbert County Engineer, all sheeting and bracing used for structure
excavation shall be removed by the Contractor prior to backfilling.
The moisture content of the backfill material shall be carefully controlled. Excessive use of
moisture that results in pumping, deflecting, or otherwise unstable material shall not be
allowed, and all such material shall be removed and reprocessed or replaced. Dry, rocky, or
otherwise poorly processed material shall also be rejected and replaced/reprocessed at the
Contractor’s expense. Compaction shall not be performed or subsequent lifts placed until the
backfill material has been properly processed and moisture-conditioned in accordance with
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
In the event that suitable backfill material is not available on the site, the Contractor shall
import Class 1 structure backfill materials as defined in Section 340.01 Definitions of these
CONSTRUCTION STANDARDS & SPECIFICATIONS, or other material approved by the
project Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer. The
Contractor shall not be required to excavate below the depths of excavation indicated on the
approved plans to provide structure backfill material.
Where pipe is connected to a structure to be backfilled, bedding and backfilling procedures
shall comply with Section 353.00 Bedding for Pipelines and Service Lines and Section 354.00
Backfill for Pipelines and Service Lines of these CONSTRUCTION STANDARDS &
SPECIFICATIONS.
The Contractor shall uniformly process, maintain proper moisture in, and properly compact
each lift throughout the backfilling process. All testing shall comply with Section 355.00
Compaction Testing of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-19
Structure backfill shall be compacted in conformance with the Moisture and Density
Requirements for Embankment Materials table in Section 341.02 Embankment Material of
these CONSTRUCTION STANDARDS & SPECIFICATIONS.
Areas deficient in degree of moisture or compaction shall be reprocessed and recompacted at
the Contractor’s expense
350.00 TRENCHING, BACKFILLING AND COMPACTING
This work shall consist of furnishing all labor, materials, tools and equipment for trenching,
bedding, backfill and compaction for all underground utilities (inclusive of “dry” utility trenches
located under roadways or within roadway R.O.W. or dedicated easement) as specified herein
and shown on the approved plans. The excavation shall be made to lines and grades shown on
the approved plans and as established by the Road & Bridge Superintendent / Elbert County
Engineer. Except where shown otherwise on the approved plans and except where the Road &
Bridge Superintendent / Elbert County Engineer gives written permission to do otherwise, all
trench excavation shall be made by open cut to the depth required to construct the pipelines as
shown on the approved plans. All excavation shall be ‘unclassified’, as defined in Section
340.01 Definitions of these CONSTRUCTION STANDARDS & SPECIFICATIONS. All
trenching shall be performed in accordance with all Occupational Safety and Health
Administration (OSHA) requirements. These regulations are described in Subpart P, Part 1926
of the Code of Federal Regulations.
All excavated material which meets the requirements for backfill materials shall be stockpiled in
a manner which shall not contaminate the excavated material, and shall be located a sufficient
distance from the trench to avoid overloading, to avoid obstructing sidewalks, driveways, or
streets, and to provide the least possible interference with traffic.
350.01 Special Conditions
A. Subsurface Investigation - Prior to the connection of any planned utility
line to an existing line, the Contractor shall expose the existing utility at
the points of connection in order to verify the elevations and materials of
construction. The Road & Bridge Superintendent / Elbert County
Engineer shall be notified a minimum of two (2) working days before such
an investigation is performed. The Contractor shall also expose utilities as
they cross each other to allow for verification of elevation and materials of
construction. The Road & Bridge Superintendent / Elbert County
Engineer shall evaluate this information and provide revisions, if required,
within three (3) working days of the completion of the investigation.
B. Underground Wire, Cable, Fiber Optic, or Similar Lines - Where
underground wire, cable, fiber optic or similar lines are encountered, they
shall be relocated as directed by the telephone service provider and in
accordance with their specifications. The Contractor shall coordinate this
work with all other phases of construction to avoid further conflicts.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-20
C. Gas and Electric Lines - Where underground gas and electric lines are
encountered, they shall be relocated as directed by the gas and electric
service provider and in accordance with their specifications. The
Contractor shall coordinate this work with all other phases of construction
to avoid further conflicts.
350.02 Removal of Water
The Contractor shall provide and maintain adequate equipment to properly remove and
dispose of all surface or ground water that enters the trench. Water shall be disposed of
without damage to adjacent property and without being a nuisance to public health and
convenience. The use of any sanitary sewer to dispose of trench water shall not be
allowed. The trench shall be dry at all times during pipe installation. Dewatering shall
be accomplished by well points, sumping or any other method approved by the Road &
Bridge Superintendent / Elbert County Engineer.
351.00 Trench Excavation for Roadways
When excavating in concrete or asphalt areas, the limits of the trench shall be string lined and
the surface cut in a vertical plane by sawing, cutting wheel or jack-hammering. If the vertical
edges of a trench in a roadway ravel during construction, they shall be trued to a vertical plane
to a point twelve (12) inches outside the limits of excavation prior to milling and placing the
resurfacing material, in accordance with the Detail Drawings.
Surface materials such as concrete and asphalt shall be disposed of independently of the
underlying soil. Suitable, non-contaminated base course and gravels shall be salvaged to be
stockpiled, protected from contamination, and reused as suitable material for backfill.
Unsuitable materials shall be disposed of by the Contractor in accordance with Section 320.01
Disposal of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
352.00 Trench Excavation for Pipelines and Service Lines
The width of the trench shall comply with the requirements set forth in these
CONSTRUCTION STANDARDS & SPECIFICATIONS and shall be sufficient to allow pipe
to be installed and backfill placed and compacted. The allowable trench width, regardless of
the type of soil encountered, the depth of excavation or method of bedding densification, shall
not exceed the outside diameter of the pipe barrel plus twenty-four (24) inches, or be less than
the outside diameter of the pipe barrel plus twelve (12) inches when measured at any point
below the top of the pipe bell, flange or collar.
Where the width of the lower portion of the trench exceeds the maximum width herein stated,
the Contractor shall furnish and install special pipe embedment or concrete encasement to
protect the pipe from the additional loading. The type and quantities of special pipe
embedment shall be determined by the pipe supplier, using trench loading criteria based upon
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-21
saturated backfill weighing one-hundred twenty (120) pounds per cubic foot and allowance
for other superimposed live loads.
352.01 Preparation of Foundation for Pipe Laying
When the excavation is in firm earth, care shall be taken to avoid excavation below the
established grade plus the required specified overdepth to accommodate the pipe bedding
material.
In case soft or otherwise unsuitable foundation material is encountered in the bottom of
the trench, the project Soils Engineer and/or the Road & Bridge Superintendent / Elbert
County Engineer may require removal and replacement with stabilization material to
provide a suitable foundation for the pipe. If the trench bottom is wet, the project Soils
Engineer shall determine whether it is stable. The bottom of sumps utilized for
dewatering shall be two (2) inches minimum below the bottom of the trench excavation
to prevent the upward flow of water into the excavation, which may result in unstable
bottom conditions.
353.00 Bedding for Pipelines and Service Lines
All pipe shall be installed with sufficient bedding material to provide a minimum of six (6)
inches of separation between the subsoil and the barrel of the pipe, and shall extend to spring
line. The bedding material shall be tamped under the haunches for the full length of the pipe
barrel to ensure support for entire length of pipe. The pipe barrel shall be uniformly
supported along the entire length of the pipe.
Bedding material for all PVC, HDPE, CPP and DIP (“flexible pipe”) shall be material that
complies with the gradation of “Fine Aggregate” as specified in Section 703.02 of the CDOT
Standard Specifications for Road and Bridge Construction, well-graded sand or squeegee
sand which complies with the following:
WELL GRADED SAND
Sieve size Total Percent
Passing by Weight
3/8 INCH 100
No. 4 70 - 100
No. 8 36 - 93
No. 16 20 - 80
No. 30 8 – 65
No. 50 2 – 30
No. 100 1 – 10
No. 200 0 – 3
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-22
SQUEEGEE SAND
Bedding material for all RCP (“rigid pipe”) shall consist of materials that meet the gradation
of “No. 67 Coarse Aggregate” as specified in Section 703.02 of the CDOT Standard
Specifications for Road and Bridge Construction
Bedding material shall be placed to a depth of twelve (12) inches above the barrel section of
all “flexible pipe” and shall be carefully tamped into place. All other pipe, unless otherwise
noted, shall be bedded to spring line. Pipe shall be installed in accordance with these
CONSTRUCTION STANDARDS & SPECIFICATIONS.
Bedding for underdrain pipe or gravel for underdrain without pipe shall be well-graded
washed rock ranging in size from one-half (½) inch minimum to one (1) inch maximum.
353.01 Bedding Compaction
All bedding material and suitable material placed to twelve (12) inches above the top of the
pipe shall be carefully compacted to at least seventy (70) percent of maximum relative density
in accordance with ASTM D4253 and 4254.
354.00 Backfill for Pipelines and Service Lines
Suitable backfill shall be as defined in Section 340.01 Definitions of these CONSTRUCTION
STANDARDS & SPECIFICATIONS. Clay and similar material with a liquid index in excess
of thirty-five (35) and a plasticity index in excess of six (6), as determined in accordance with
AASHTO T89 and T90, shall not be considered suitable for backfilling in trenches located in
improved streets, roads, highways and thoroughfares, unless approved by the Road & Bridge
Superintendent / Elbert County Engineer.
When the excavated material is unsuitable for compaction, import material shall be approved
by the project Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer
prior to placement.
Refer to Section 822.02 Controlled Low Strength Materials (CLSM) of these
CONSTRUCTION STANDARDS & SPECIFICATIONS for requirements of structure
backfill (“Flowable Fill”) used to backfill pipeline and service line trenches.
Materials used above the subgrade level shall comply with the requirements for sub-base and
base course materials as defined in Section 600 Hot Bituminous Pavement (Asphalt) Mix
Design and Construction of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
Sieve size Total Percent
Passing by Weight
3/8 inch 100
No. 200 0-5
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-23
Bracing installed to prevent cave-ins shall be withdrawn in a manner that shall maintain the
desired support during the backfill operations. Driven sheet pilings shall be cut off at or
above the top of pipe, and the portion below the cut-off line shall be left in the ground.
354.01 Backfill Compaction
Trench backfill shall be placed in loose six (6) inch lifts, processed and moisture-
conditioned, and each lift thoroughly consolidated by tamping, vibrating, or a
combination thereof, until the moisture content and the relative compaction complies
with the values shown in the Moisture and Density Requirements for Embankment
Materials table in Section 341.02 Embankment Material of these CONSTRUCTION
STANDARDS & SPECIFICATIONS for the various soil classifications and relative
compaction.
For new landscape areas with trees, compaction shall be between eighty-five (85) and
ninety (90) percent of the maximum Standard Proctor dry density in the top two (2) feet
of soils below finished grade. Where sidewalk or concrete trail will be constructed, soils
shall be scarified, moisture treated and recompacted two (2) feet wider than the footprint
of the sidewalk or trail until the moisture content and the relative compaction complies
with the values shown in the
Moisture and Density Requirements for Embankment Materials table in Section
341.02.01 Embankments Twelve (12) Feet or Less in Depth of these CONSTRUCTION
STANDARDS & SPECIFICATIONS.
Backfill of utilities, pipes, culverts, or other miscellaneous structures located in areas that
will not have a hard surface shall be placed in six (6) inch lifts at ninety (90) percent of
the maximum Standard Proctor dry density and within two (2) percent of the optimum
moisture content. All other requirements for particle size and processing shall be met.
Processing, moisture-conditioning, and compaction shall be performed with equipment
that is suitable for the specific field conditions. The equipment used shall be sufficient to
obtain uniform processing, uniform moisture-conditioning, and uniform compaction
throughout each lift of material placed. Vertical structures or other small, tight areas
shall be compacted by hand or by equipment small enough to provide compaction within
three (3) inches of the structure (or in between dual utility lines). Use of CLSM may be
approved by the Road & Bridge Superintendent / Elbert County Engineer for such areas.
It is the responsibility of the contractor to protect the installed pipe from damage resulting
from compactive efforts. In no case shall soil compaction operations be performed
within eighteen (18) inches (vertically) of rigid pipe or within twenty-four (24) inches
(vertically) of flexible pipe; however, the material placed within this zone shall comply
with the requirements of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
Flooding or jetting of trenches shall not be allowed without written approval from the
Road & Bridge Superintendent / Elbert County Engineer
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-24
355.00 Compaction Testing
Compaction testing shall be performed at a minimum frequency of one (1) test for every one-
thousand (1,000) yds and no less than two (2) tests per day for embankment fill materials.
Compaction testing shall be performed at a minimum frequency of (1) test per two-hundred
(200) yds3 of backfill material or at least one (1) test per two-hundred and fifty (250) lineal
feet per lift, whichever controls. Sand cone testing or other means of verifying nuclear
moisture and density test results shall also be performed.
Testing shall be performed at various depths and locations, and at all vertical structures. The
project Soils Engineer and/or the Road & Bridge Superintendent / Elbert County Engineer
may require additional testing around structures, manholes, valve boxes, etc.
Field test results shall be submitted to the Road & Bridge Superintendent / Elbert County
Engineer within twenty-four (24) hours of the test or on the next working day. In no case
shall fill or backfill be placed on materials that did not pass moisture and density testing.
Moisture and density testing shall be performed by a qualified technician who works under
the direct supervision of a Colorado Registered Professional Engineer. Final soil compaction
reports shall be prepared and signed by a Colorado Registered Professional Engineer, and
who is qualified to prepare such reports. Reports shall be submitted to the Road & Bridge
Superintendent / Elbert County Engineer within one (1) week of the test.
360.00 ROADWAY EXCAVATION, BACKFILL AND COMPACTION
Prior to placement of street subgrade, base, paving and concrete materials, utilities shall be
installed, utility service lines shall be stubbed to the edge of the R.O.W., and all trenches shall be
backfilled and properly compacted.
Roadway excavation shall be in accordance with ‘unclassified excavation’ as defined in Section
340.01 Definitions of these CONSTRUCTION STANDARDS & SPECIFICATIONS, except for
areas of ‘rock excavation’, as defined in the same Section. Material and excavation for the
roadway backfill shall comply with Section 341.02 Embankment Material of these
CONSTRUCTION STANDARDS & SPECIFICATIONS.
All roadway backfill shall be compacted to densities and moisture contents shown in the
following table, unless otherwise required by the project Soils Engineer and the Road & Bridge
Superintendent / Elbert County Engineer:
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-25
Soil Classification
AASHTO M145
Relative Compaction
By Standard Proctor
ASTM D698 or
AASHTO T99
(percent compaction)
Relative Compaction
By Modified Proctor
ASTM D1557 or
AASHTO T180
(percent compaction)
Moisture Content
Range
(with respect to Optimum)
A-1, A-2, A-3 - 95 -2 to +2
(based on AASHTO T180)
A-4, A-6, A-7 95 - -1 to +3
(based on AASHTO T99)
Prior to placement and compaction of roadway fill, all existing rubble and organic material shall
be removed down to existing ‘suitable material’, as defined in Section 340.01 Definitions of
these CONSTRUCTION STANDARDS & SPECIFICATIONS. The existing suitable material
shall then be scarified and roadway fill placed in accordance with Section 341.01 Preparation of
Embankment Subgrade of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
361.00 Subgrade
Refer to Section 350.00 TRENCHING, BACKFILLING AND COMPACTING and Section
360.00 ROADWAY EXCAVATION, BACKFILL AND COMPACTION of these
CONSTRUCTION STANDARDS & SPECIFICATIONS for backfill of concrete flatwork
and structures.
Refer to Section 934.00 Construction of Pavement Sections of these CONSTRUCTION
STANDARDS & SPECIFICATIONS.
Subgrade and subgrade treatments described herein shall consist of soils directly under
pavements and concrete curb or sidewalk and shall conform to the lines, grades, and cross-
sections shown on the approved plans. All work shall be observed and tested by the project
Soils Engineer or representative.
The construction of subgrade shall consist of preparing the approved subgrade material to
form a firm, stable foundation.
Each layer of material shall be placed and spread so that after compaction it shall conform to
the width and crown of the typical cross-sections.
Soft and yielding material and portions of the subgrade which show deflection shall be
scarified and recompacted or removed and replaced with base course or other material
approved by the project Soils Engineer and the Road & Bridge Superintendent / Elbert
County Engineer, and compacted as specified herein.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-26
The wetting of subgrade layers shall be done with sprinkling equipment of a type that ensures
uniform and controlled distribution of the water. All wetting shall be done by uniformly
sprinkling each layer of material being placed with only the amount of water needed to obtain
maximum density of the material.
Concurrently with the wetting operations, the material shall be uniformly compacted by
rolling. Rolling equipment shall consist of one or more of the following: rubber tired roller,
sheepsfoot roller and flat wheel steel roller.
After excavation and embankment construction are complete and the subgrade brought to
final grade, it shall be rolled with a rubber-tired roller which is a minimum size of eight (8) to
twelve (12) tons and other compaction equipment as required to bring the subgrade to the
density and moisture content shown in the following table, unless otherwise required by the
project Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer:
Soil Classification
AASHTO M145
Relative Compaction
By Standard Proctor
ASTM D698 or
AASHTO T99
(percent compaction)
Relative Compaction
By Modified Proctor
ASTM D1557 or
AASHTO T180
(percent compaction)
Moisture Content
Range
(with respect to Optimum)
A-1, A-2, A-3 100 - -2 to +2
(based on AASHTO T180)
A-4, A-6, A-7 95 - -1 to +3
(based on AASHTO T99)
No concrete or asphalt pavement, subgrade or base course shall be placed on unsuitable
material.
361.01 Over-Excavation for Expansive Soils
An Over-Excavation Permit shall be required in accordance with Section 151.00
Public/Private Improvement Permit (PPIP), Grading Permit and Over-Excavation Permit
of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
Soils with a Plasticity Index (P.I.) over ten (10) and less than thirty (30) shall be over-
excavated and recompacted to ninety-five (95) percent of maximum Standard Proctor dry
density as determined by ASTM D698 or AASHTO T99. The moisture content shall be
maintained between the optimum moisture content and three (3) percent over the
optimum moisture content (+3%). There shall be a minimum of twelve (12) inches of
soil stabilization below the pavement section included as part of the depth of treatment,
and the total depth of treatment shall be in accordance with the approved pavement
design.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-27
Soils with a P.I. of thirty (30) or greater may require moisture treatment followed by
pozzolan treatment (lime, cement, fly ash, kiln dust) or other subgrade stabilization
method approved by the Road & Bridge Superintendent / Elbert County Engineer. Refer
to the Minimum Over-Excavation Requirements table below. Stabilized subgrade shall
extend to the back of the sidewalk for streets with attached sidewalks, and to one foot (1’)
behind the back of the curb for streets with detached sidewalks.
The Road & Bridge Superintendent / Elbert County Engineer may waive the pozzolan
treatment requirement for onsite soils that have P.I.’s of thirty (30) or greater when the
following conditions exist:
• The soils have a moisture content between the optimum moisture content and
three (3) percent over the optimum moisture content (+3%);
• The soils have a maximum Standard Proctor dry density of at least ninety-five
(95) percent, and
• The soils exhibit a swell potential of less than two (2) percent as determined
under a two-hundred (200) psf surcharge.
In lieu of subgrade stabilization, a composite section designed by a Colorado Registered
Professional Engineer and consisting of at least twelve (12) inches of base course may be
approved by the Road & Bridge Superintendent / Elbert County Engineer.
Unless otherwise recommended by the project Soils Engineer and approved by the Road
& Bridge Superintendent / Elbert County Engineer, the following minimum over-
excavation requirements shall apply for expansive soils:
Minimum Over-Excavation Requirements
PLASTICITY INDEX DEPTH OF TREATMENT
Local and Collector Streets Arterials
10-29 1 feet 2 feet
30-40 2 feet 3 feet
> 40 4 feet 4 feet
361.02 Base Course (For Composite Sections)
361.02.01 Materials
Base course subgrade shall consist of a foundation course composed of crushed
gravel, recycled concrete or crushed stone and filler, constructed on the prepared
subgrade. Material composed of uniform size particles, or which contains pockets
of excessively fine or excessively coarse material, shall not be approved for use.
Materials and construction shall be in accordance with the requirements of
Section 304 of the CDOT Standard Specifications for Road and Bridge
Construction. Gradation shall be Class 5 (1½” maximum) or Class 6 (¾”
maximum), in accordance with Table 703-2 of CDOT Standard Specifications for
Road and Bridge Construction.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-28
361.02.02 Construction
All work shall be observed and tested by the project Soils Engineer or
representative. The base course material, aggregate base or recycled concrete,
shall be placed on the previously prepared subgrade at the locations and in the
proper quantities to conform to the cross-sections shown on the approved plans
and as directed by the Road & Bridge Superintendent / Elbert County Engineer.
Geotextile fabric shall be installed if required on the approved plans. Placing and
spreading shall be done by means of a spreader machine, moving vehicle, motor
grader, or by other approved equipment methods. The material shall be placed
without segregation. Any segregated areas shall be removed and replaced with
uniformly graded material at the Contractor's expense.
The thickness of each base course layer shall not exceed six (6) inches before
compaction. If the required depth exceeds six (6) inches, and is less than twelve
(12) inches, material shall be placed in two (2) or more lifts of approximate equal
thickness. If uniform density cannot be obtained by six (6) inch lifts, the
maximum lift thickness shall not exceed four (4) inches.
Base course material shall not be placed on a dry or dusty soil foundation which
could cause rapid dissipation of moisture from the base course material and hinder
or preclude proper compaction.
Excessively dry soil foundations shall have water applied to them and shall be
reprocessed and recompacted. If, at any time, the subgrade construction is
subjected to rain, snow or other significant events, the project Soils Engineer shall
evaluate the affected areas prior to continuing with subgrade preparation and shall
make a recommendation to the Contractor and to Elbert County.
Rolling shall be continuous until the base course material has been compacted
thoroughly in accordance with Section 304 of the CDOT Standard Specifications
for Road and Bridge Construction. Water shall be uniformly applied during
compaction to obtain the specified moisture content and to aid in consolidation.
The surface of each layer shall be uniformly maintained during compaction
operations.
The prepared base course surface shall be smooth and free of ruts and
irregularities, and shall be true to line and grade shown on the approved plans and
as directed by the Road & Bridge Superintendent / Elbert County Engineer. The
base course shall be maintained in this condition by watering, drying, rolling,
and/or blading until the asphalt or concrete flatwork is placed. The surface
tolerance of the base course shall be in accordance with Section 301.04 of the
CDOT Standard Specifications for Road and Bridge Construction.
361.03 Lime-Treated Subgrade
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-29
When required, lime treated subgrade shall comply with Section 307 of the CDOT
Standard Specifications for Road and Bridge Construction. Lime-treated subgrade shall
extend to the back of the sidewalk for streets with attached sidewalks, and one (1) foot
behind the back of the curb for streets with detached sidewalks, as shown in the Detail
Drawings.
Alternative methods of soil stabilization may be allowed with approval of the Road &
Bridge Superintendent / Elbert County Engineer. Soil mix design procedures shall
comply with the CDOT Standard Specifications for Road and Bridge Construction.
Sulfate testing shall be performed on streets to have lime-treated subgrade. The initial
sampling and testing frequency shall be every five hundred (500) feet per lane. Each
sample shall consist of soils evenly distributed in the top twenty-four (24) inches of the
subgrade to be lime-treated. Where sulfates greater than 0.03 ppm or 0.003% by volume
are discovered, additional sampling and testing within a one-hundred (100) foot radius of
the “hot” soils shall be performed. Testing shall occur until the areas with sulfates
greater than 0.03 ppm are isolated and removed.
361.04 Proof-Roll Observation and Testing
Proof-roll observation and testing (proof-rolling) may be required to determine whether
certain areas of subgrade meet compaction requirements. Where required by the Road &
Bridge Superintendent / Elbert County Engineer, proof-rolling shall be performed as
designated with a water truck loaded to a minimum of 36,000 lb. Tires shall be inflated
to a minimum of seventy (70) pounds per square inch and a maximum pressure of ninety
(90) pounds per square inch. Air pressure in the tires shall be maintained within a
tolerance of five (5) pounds per square inch.
Within the twenty four (24) hour time period prior to paving, subgrade compaction
testing and proof -rolling with a water truck shall be required.
After passing compaction tests, the Contractor and/or Owner’s representative shall proof-
roll the areas. No proof-roll inspections shall be performed until all underground utility
testing is complete. Subgrade areas failing compaction testing or proof-rolling shall be
delineated and reprocessed and/or removed and replaced in a manner approved by the
project Soils Engineer and the Road & Bridge Superintendent / Elbert County Engineer.
Such procedures may include over-excavation, scarification, moisture-conditioning,
recompaction, and/or replacement with suitable materials that comply with the moisture
and density requirements. In addition to complying with moisture and density
requirements, all subgrade materials shall exhibit stability during proof-rolling.
Additional compaction testing and proof-rolling may be required at the discretion of the
Road & Bridge Superintendent / Elbert County Engineer. All proof-rolling operations
shall be at the Contractor’s expense.
SOILS AND EARTHWORK SECTION 300
CONSTRUCTION STANDARDS & SPECIFICATIONS 2007 Edition PAGE 300-30
370.00 RESTORATION AND CLEAN UP
At all times during construction, the Contractor shall maintain the site, including partially
finished structures, material stockpiles and other like areas, in a reasonable state of order and
cleanliness.
The grade and condition of all unsurfaced areas shall be restored to a condition equal to or better
than the grade and condition immediately prior to construction, unless otherwise shown in the
approved plans and approved by Elbert County. The Contractor shall restore or replace all
seeded areas, sod, trees, landscaping materials, landscape irrigation systems, fences, and any
other items, to a condition equal to or better than before the work began and to the satisfaction of
the Road & Bridge Superintendent / Elbert County Engineer. All grassed areas shall be reseeded
or resodded in accordance with Section 1000 LANDSCAPING STANDARDS FOR
DEVELOPMENT PROJECTS of these CONSTRUCTION STANDARDS &
SPECIFICATIONS, and the Contractor shall be responsible for maintaining these areas until
substantial growth occurs and Construction Acceptance. Refer to Section 200 ACCEPTANCE
PROCEDURES of these CONSTRUCTION STANDARDS & SPECIFICATIONS.
All pavement and concrete flatwork shall be restored or replaced to a condition equal to or better
than before the work began and to the satisfaction of the Road & Bridge Superintendent / Elbert
County Engineer.
In the event of failure of the Developer or Contractor to complete work, correct deficiencies, or
clean up a project site in a reasonable time period, Elbert County has the right to draw upon the
performance guarantee, as specified in the Subdivision Improvement Agreement.